Low oxygen biologically mediated nutrient removal

ABSTRACT

The present invention is directed to a substantially odorless biologically mediated treatment process for solid and liquid organic wastes. The present invention also provides for a novel nutrient rich humus material produced from the biologically mediated treatment process. The bioconversion process of the present invention results from low electron acceptor concentrations and high quantities of microorganisms in a diverse microbial community.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. Ser. No.12/542,122 filed Aug. 17, 2009, issuing on Feb. 1, 2011 as U.S. Pat. No.7,879,589, which is a divisional application of U.S. Ser. No. 11/592,513filed Nov. 3, 2006, now U.S. Pat. No. 7,575,685, which is acontinuation-in-part of U.S. Ser. No. 11/106,751 filed on Apr. 15, 2005,now U.S. Pat. No. 7,431,839 which is a continuation-in-part of U.S. Ser.No. 10/600,936, filed on Jun. 20, 2003, now U.S. Pat. No. 6,908,495, andclaims priority to U.S. patent application Ser. No. 09/709,171 filed onNov. 10, 2000, now U.S. Pat. No. 6,689,274, all of which areincorporated by reference in their entireties. U.S. application Ser. No.10/600,936, filed on Jun. 20, 2003, now U.S. Pat. No. 6,908,495 and U.S.patent application Ser. No. 09/709,171 filed on Nov. 10, 2000, now U.S.Pat. No. 6,689,274 are each expressly incorporated herein in itsentirety by reference thereto.

The present invention relates to a novel process for the biologicallymediated treatment of solid and liquid organic wastes, particularlyanimal farm wastes, including the removal of nutrients from such wastes,such as, for example, phosphorus and nitrogen.

BACKGROUND OF THE INVENTION

Everyday, organic waste streams are created that need to be treated insome form or manner before they are disposed of. For example, organicwaste streams in conventional municipal waste and wastewater plants,food manufacturing facilities, industrial factories, and animal farmsare typically treated either physically, chemically, and/or biologicallybefore combining the effluent(s) with a water body, land applying theeffluent(s), or disposing of the effluent(s) in an alternative manner,such as by removal from the site for further treatment elsewhere.

Organic waste treatment technologies have progressed significantly inrecent years due, in part, to increased public awareness, lobbying,legislation and regulatory oversight. In some instances, treatmenttechnologies have been developed upon the realization that entirely newand useful products could be created from the wastes thereby generatingnew business opportunities for technology innovators. Often times, newor improved technologies are created for purely economic reasons.

Presently, most treatment technologies for organic wastes typicallyinclude some form of biological treatment wherein biological organismsstabilize organic matter and remove soluble and/or nonsettleablecolloidal solids to reduce the content of microbial substrates(nutrients such as phosphorus, sulfur and particularly nitrogen andother organic biodegradable materials as measured by the totalbiochemical oxygen demand (BOD) test). The microbial substrates,particularly if left untreated, are known to pollute surface andsubsurface water supplies and negatively impact air and soil quality.Suspended growth processes, attached-growth processes and combinedsuspended and attached growth processes are used for biologicaltreatment of organic wastes to reduce substrate quantities in thetreated effluents. Often times, waste streams and the microbialsubstrates therein are also subjected to additional treatment processesprior to the disposal of process effluents such as, for example,screening, digestion, composting, disinfection, chemical precipitation,and/or phosphorus removal.

With increasing human population density, municipal wastewater treatmentfacilities, animal farming facilities, and industrial and foodprocessing treatment facilities have come under increasing pressure toupgrade, modify, or supplement their treatment processes to improve thequality of system effluent discharges as well as the air in and aroundsuch facilities to further protect the environment, and human and animalhealth. A particularly persistent problem addressed by the presentinvention is the treatment of animal excrement containing highconcentrations of microbial substrates which, in typical animaltreatment systems, not only pollute surface and subsurface watersupplies, but also negatively impact air and soil quality. The effluentdischarges from these animal treatment systems oftentimes containundesired amounts of available nitrogen and phosphorus which have beenlinked to detrimental effects in water bodies such as, for example,accelerated eutrophication and aquatic growths. Further, presenttreatment alternatives for organic waste streams, such as animalexcrement, frequently generate and exacerbate the offensive odors andemissions of atmospheric pollutants.

The input to an organic waste biological treatment process usuallycontains concentrations of phosphorus and other nutrients such as, forexample, nitrogen. This will hold for flowable organic waste streams orfor non flowable wastes, such as scrapped fresh manure, which areconverted into an aqueous stream by mixing with a recycle stream from atreatment process. For municipal wastewaters, the typical influentphosphorus (P) to nitrogen (N) load ratio (the “P/N Ratio”) is about0.18. Metcalf & Eddy, Wastewater Engineering—Treatment and Reuse, 4^(th)Ed., Tchobanoglous, George et al., McGraw-Hill, Inc. (2003). P/N Ratiosfor animal farm wastes are typically about 0.18 (dairy) to 0.30 (swineand layer chickens). ASAE Standard D384.1, 2003. Industrial waste andfood industry waste P/N Ratios are less consistent than those formunicipal or animal wastes and largely depend on the products and theprocesses. Some of the nutrients in such organic inputs will beincorporated into the microbial cell mass as a result of the biologicaltreatment process and may be removed from treatment systems as acomponent of the solids (sometimes referred to as sludge). The portionof the nutrients remaining in the waste stream (whether converted orunconverted by the biological treatment process) will be discharged withthe liquid effluent.

In some processes, the amount of a single nutrient can be a limitingfactor to the biological treatment process and nearly all of thatnutrient is converted and incorporated into the microbial cell massleaving little, if any, portion of that nutrient in the process liquideffluent. In conventional biological wastewater treatment processeswhere the BOD and COD concentrations are not limiting, and when the P/NRatio is appropriately low relative to the requirements of normallygrowing microbial populations, the vast majority of the phosphorus willbe assimilated into biomass and the phosphorus in the liquid effluentwill in turn be relatively low. This will generally be true if the P/NRatio is less than about 0.16 (as long as no significant nitrificationand denitrification is occurring in the system in which case nitrogengas is typically released increasing the P/N Ratio that can be treated),since this is the P/N Ratio commonly found in slowly growing microbialcells. In effect, the phosphorus and nitrogen in the wastewatertreatment system is assimilated into microbial cells.

In the low oxygen organic waste biologically mediated conversion systemfor an organic waste described in U.S. Pat. No. 6,689,274 (Northrop, etal.), in order to accomplish a similar result for biological conversionof phosphorus and nitrogen, the P/N Ratio needs to be somewhat lowerthan about 0.16 because significant amounts of nitrogen are dischargedto atmosphere as dimolecular nitrogen gas and hence is not available forincorporation into microbial cells. Thus, P/N Ratios of about 0.07 orless would normally be required in the organic influent waste stream toachieve equivalent low effluent phosphorus discharges as seen inconventional biological treatment systems. The phosphorus content in thetreated effluent depends upon the incorporation of phosphorus intomicrobial cells and other settleable and/or suspended solids and thenseparating those cells and solids from that effluent by collecting themas a portion of the harvested humus material generated by the process.Any phosphorus not converted into insoluble and/or particulate form, aswell as any insoluble and/or particulate nutrients not collected in theharvested humus material will be discharged in the system effluent. Onaverage, phosphorus removal by biological treatment processes withsludge wasting may range from 10 to 30 percent of the influent amount.Metcalf & Eddy, Wastewater Engineering, Treatment, Disposal, Reuse,3^(rd) Ed., Tchobanoglous, George et al., McGraw-Hill, Inc. (1991) at p.726. According to the process described in U.S. Pat. No. 6,689,274, loweffluent discharges of phosphorus would contain less than about 50percent of the influent phosphorus load (greater than about 50 percentremoval). Preferable discharges would contain less than about 20 percentof the influent phosphorus load (greater than about 80 percent removal).

When the influent waste stream to a biological wastewater treatmentprocess contains P/N Ratios which are higher, sometimes substantiallyhigher, than 0.16, the resulting concentration of soluble phosphorus inthe effluent stream may be higher than desired and it is sometimesnecessary and/or desirable to lower such effluent phosphorus discharges.One method known in the art to try to lower such effluent phosphorusdischarges is the addition of an anaerobic zone to an aerobic wastewaterbiological treatment process. The expected increase in the phosphoruscontent of the resultant biomass and sludge is supposed to reduceeffluent phosphorus discharges. This phosphorus conversion process isgenerally known as the “Bio-P” process and the conversion mechanism isunderstood to be as follows:

A community of micro organisms referred to as Phosphorus AccumulatingOrganisms (“PAOs”), when exposed to alternating aerobic and anaerobicenvironments, will take up excess amounts of phosphate ions and storethem as polyphosphate. When these PAOs encounter anaerobic conditionsthey will use the energy stored in the polyphosphate, thereby decreasingtheir polyphosphate stores, and will accumulate acetate or othervolatile fatty acids, storing these compounds in polymer form, usuallyas polyhydroxybuteric acid. When these organisms then encounter aerobicconditions they will oxidize the stored organic polymers and otherenergy sources using electron acceptors (e.g. oxygen) from the aerobicenvironment and use the energy to form energy rich polyphosphate. Thepolyphosphate is stored so that the energy it contains may be used whenanaerobic conditions recur, which allows the PAOs to displace otherheterotrophic microorganisms that can not take advantage of the storedenergy to thrive under anaerobic conditions. This relative energyadvantage in the anaerobic environment leads to the dominance of PAOsover other phosphate uptake organisms which utilize oxygen as anelectron acceptor. See Janssen, P. M. J., Biological Phosphorus Removal,Manual for design and operation, IWA Publishing (2002) at p. 17. Whenthe PAOs use the energy stored in the polyphosphate in the anaerobicsub-zone, soluble phosphorus is released. When the PAOs return to theaerobic zone soluble phosphorus is absorbed and again converted topolyphosphate removing it from the aqueous phase and incorporating it asinsoluble or particulate microbial biomass. If this biomass is thenremoved under aerobic conditions before the anaerobic environment isencountered, the phosphorus is removed from the system. Metcalf & Eddy,Wastewater Engineering—Treatment and Reuse, 4^(th) Ed., Tchobanoglous,George et al., McGraw-Hill, Inc. (2003) at p. 623-627.

Recently, the Bio-P mechanism has been found to work if the aerobicprocess is replaced with an anoxic process containing nitrate and/ornitrite instead of molecular oxygen. Janssen, P. M. J., BiologicalPhosphorus Removal, Manual for design and operation, IWA Publishing(2002) at p. 16. However, the efficiency of the process using an anoxicenvironment instead of an aerobic environment is lower than thatobtained when molecular oxygen in an aerobic environment is used. Thisoccurs because it takes energy to extract oxygen from electron acceptorssuch as nitrate or nitrite and so the net production of usable energyfrom a substrate must be decreased by this amount (usually by about 40percent when the electron acceptor is nitrate, see Janssen at pg. 20).

Despite this reduced efficiency, the addition of an anaerobicenvironment to a nitrate containing anoxic process, and the recycling ofthe anoxic liquid through the anaerobic environment, allows denitrifyingPAOs to have a similar Bio-P selective advantage over normal, non-PAOdenitrifiers. However, prior to the Applicants' discovery, thisselective advantage was expected to disappear as the concentration ofnitrate decreased to low levels because, compared to a normal non-PAOdenitrifier, it would become more difficult for the PAO to acquire theadditional electron acceptors it needs to generate the extra energyrequired to build and use the various PAO polymers. Thus, theconcentration of nitrate or nitrite is rate limiting for PAOdenitrifiers at significantly higher levels than it is for normalnon-PAO denitrifiers.

This rate limiting effect from concentrations of nitrate or nitrite isnot a problem if other electron acceptors are available in sufficientquantities in the aerobic or anoxic environment. However, inenvironments with low electron acceptor concentrations, a cell would beless likely to get the additional ions it needs to grow and functioncompared to a normal denitrifier, and hence would not be competitivewith such normal denitrifiers in that environment. The selectiveadvantage which the anaerobic environment provided for PAO's woulddisappear. As the whole system approaches the conditions of an anaerobicenvironment (lower and lower concentrations of electron acceptors) theadvantage of a separate anaerobic environment would be expected todisappear.

Despite the expectation that low concentrations of nitrate would makeanoxic Bio-P ineffective, applicants have surprisingly found that if ananaerobic zone is added to or within the low oxygen organic wastebioconversion system described in U.S. Pat. No. 6,689,274 (Northrop etal.), and if the process liquid is recycled through the system,including the anaerobic zone, a significant transformation occurswhereby more soluble phosphorus is converted into particulatephosphorus. This transformation of soluble phosphorus into particulateform occurs even though the concentrations of molecular oxygen, nitrate,and nitrite are very low.

Even more surprising has been the discovery that once the transformationoccurs, whereby more soluble phosphorus is converted into particulatephosphorus in a system which experiences alternating exposure toanaerobic and low electron acceptor environments, this enhancedphosphorus conversion (transforming into particulate form) ability canpersist even when the anaerobic environment is subsequently removed fromthe process.

Thus, applicants have surprisingly discovered that certain populationsof PAOs, and especially certain populations of denitrifying PAOs, cancontinue to accumulate significant levels of particulate phosphorus evenwhen living in environments which have low concentrations of electronaccepting substances (such as oxygen, nitrite, nitrate) and that thesepopulations of PAOs maintain this conversion ability whether theyfunction exclusively in low electron acceptor environments or whetherthey live in environments which vary between anaerobic and low electronacceptor conditions at either a microscopic or macroscopic scale.

In general, denitrifying PAOs are not expected to have a selectiveadvantage to grow in low electron acceptor environments without aphysically separated and defined anaerobic environment. However,Applicants have determined that the surprising ability to do so can beinduced in a variety of ways that include, but are not limited to: 1.recycling the denitrifying PAOs between anaerobic and low electronacceptor zones containing relatively high phosphorus to nitrogen ratios(greater than about 0.16 and as high as about 0.3 to 0.5) until thephosphorus conversion ability is developed and then removing theanaerobic zone from the system, 2. seeding the low electron acceptorenvironment described in U.S. Pat. No. 6,689,274 and U.S. applicationSer. No.10/600,936 containing relatively high phosphorus to nitrogenratios (greater than about 0.16 and as high as about 0.3 to 0.5) withnitrifying and denitrifying PAOs which already are adapted to grow inthe low electron acceptor environment without a physically separated anddefined anaerobic environment, perhaps from another treatment system orfrom a PAO production site; and 3. in a system without a physicallydefined anaerobic environment but with a low electron acceptorenvironment, through varying low concentrations of electron acceptors inlocal zones (microenvironments) of a large environment containingrelatively high phosphorus to nitrogen ratios (greater than about 0.16and as high as about 0.3 to 0.5) so that a population of denitrifyingPAOs evolves which is tolerant to and will grow in any such low electronacceptor environment as evidenced by particulate phosphorusconcentrations.

There is clearly a competitive advantage for denitrifying PAOs which areable to grow exclusively in low electron acceptor environments and whichcan also grow in environments which have both low electron acceptorzones and anaerobic zones (microenvironments). Incorporation of thesepopulations into organic waste treatment systems with relatively highphosphorus to nitrogen ratios allows such waste streams to besuccessfully treated within low electron acceptor environments withoutthe necessity of designing, building, and operating additional systemsor subsystems with discrete anaerobic environments. Capital investmentsare decreased, maintenance costs are reduced and land use is minimized.

Applicants have therefore discovered an improved process for thebiologically mediated conversion of organic waste and removal ofnutrients from the waste. This process operates at low electron acceptorconcentrations while maintaining high quantities of diverse populationsof microorganisms in the process. The present invention addresses manyof the problems associated with municipal, domestic, industrial, foodindustry, animal husbandry and other organic wastes, by providing anattractive and efficient means to resolve ecological problems associatedwith the treatment of organic wastes. The present invention addressesthe odor emission problem common to organic wastes as well as theproblem associated with high nutrient effluent discharge concentrationsthrough the efficient, substantially odorless, biologically mediatedconversion of waste excrement materials or a vast array of other organicwastes into stable, economically and/or ecologically beneficialmaterials.

Thus, it is an object of the present invention to provide an improvedprocess for the efficient, substantially odorless, biological treatmentof organic waste.

It is another object of the present invention to provide an improvedprocess for the efficient, substantially odorless, biological treatmentof organic waste which converts a substantial portion of the solublephosphorus into particulate form.

It is another object of the present invention to provide an improvedprocess to create a biologically active, ecologically beneficial,substantially odorless humus material through the biologically mediatedconversion of phosphorus containing organic waste, in which most of thephosphorus is captured in the humus material.

It is another object of the present invention to provide an improvedprocess for the efficient, substantially odorless, biologically mediatedtransformation of organic wastes into suitable materials for recyclingto the environment.

It is another object of the present invention to provide an improvedprocess to create a biologically active, ecologically beneficial,substantially odorless humus material through the biologically mediatedconversion of organic waste, particularly animal excrement.

It is a still further object of the present invention to create PAOswith the capability of accumulating significant levels of particulatephosphorus even when living in environments which have lowconcentrations of electron accepting substances (such as oxygen,nitrite, nitrate) with and/or without subjecting the PAOs to discreteanaerobic conditions in a physically defined and separate environment.

It is a still further object of the present invention to provide aprocess to create a biologically active, and/or nutrient rich, organicsoil.

It is a still further object of the present invention to provide aprocess to create a biologically active, and/or nutrient rich, feedmaterial or supplement.

These and other objects will be apparent from the following descriptionof the invention.

SUMMARY OF THE INVENTION

The present invention relates to a low oxygen, high microorganism mass,biologically mediated organic waste conversion process, themicroorganisms in the process, and the product of the process. In theprocess, organic waste, such as animal excrement, containingconcentrations of potentially polluting or environmentally harmfulsubstrates, is biologically treated and stabilized. The process performssimultaneous nitrification and denitrification on organic waste streamsand converts soluble phosphorus to particulate form. The presentinvention also includes the discovery of a unique ecological niche inwhich PAOs can convert soluble forms of phosphorus to particulate formwhen living in environments which have low concentrations of electronaccepting substances (such as oxygen, nitrite, nitrate) whether theyfunction exclusively in low electron acceptor environments or whetherthey live in environments which vary between anaerobic and low electronacceptor conditions at either a microscopic or macroscopic scale. Thus,the present invention furthermore relates to a low oxygen, highmicroorganism mass, biologically mediated organic waste conversionprocess with increased nutrient conversion. The present invention alsoincludes the ecologically beneficial, nutrient rich, valuable organichumus material created by the processes of the invention.

Applicants have discovered that if specific environmental conditions aremaintained in a biological wastewater treatment process, a naturalmicrobial community will evolve that will seek a state of dynamicequilibrium within a plurality of desired ecological niches. Applicantshave surprisingly determined that a high mass of microorganisms can bemaintained in combination with a low dissolved oxygen concentrationresulting in a substantially odorless, efficient biologically mediatedconversion of organic waste wherein simultaneous nitrification anddenitrification occurs in a low electron acceptor environment, such as,for example, low concentrations of oxygen, nitrate or nitrite, eitheralone or in any combination thereof. The process provides forsimultaneous treatment and stabilization of the organic waste, issubstantially odorless and is more efficient than present biologicaltreatment systems.

Applicants have also surprisingly determined that certain unexpectedresults can be achieved within the low electron acceptor environment ofthe process when (i) certain environmental conditions are temporarilyadded to induce certain microorganism abilities; (ii) certain microbialpopulations having induced abilities are added, and/or (iii) the lowconcentrations of electron acceptors are varied in local zones of alarge environment containing relatively high phosphorus to nitrogenratios (greater than about 0.16 and as high as about 0.3 to 0.5) toinduce certain microorganism abilities. More specifically, the amount ofsoluble nutrients, such as, for example, phosphorus, in the waste thatis converted into particulates can be increased.

Accordingly, Applicants have surprisingly discovered a process tosimultaneously treat and stabilize organic waste, which is substantiallyodorless and more efficient than present biological treatment systems,and which provides efficient biologically mediated conversion of organicwaste and nutrients, wherein simultaneous nitrification anddenitrification occur in a low electron acceptor environment, such as,for example, low concentrations of oxygen, nitrate or nitrite, eitheralone or in any combination thereof, without discrete anaerobicconditions in a physically defined and separate environment. The processutilizes (and in some cases, establishes) what shall be referred tohereinafter as micro-electron acceptor PAOs (“MEAPAOs”) which functionin the low electron acceptor environment of the invention containinghigh microorganism mass, the MEAPAOs possessing enhanced nutrient uptakeor carrying abilities. The presence and continued existence ofpopulations of these MEAPAOs with the capability of converting solublenutrients into particulate form in the low electron acceptor environmentresult in unexpected nutrient removal by the overall treatment system.

The resulting humus material of the process has commercial value, is notof unpleasant odor and can be safely maintained in open storage withoutsignificant migration of compounds. The process also manages water,which may have been combined with organic waste to optionally provide anutrient rich aqueous fertilizer, which can be used to irrigate crops,or as a clean, generally low nutrient liquid, that with furtherprocessing is potentially suitable for discharge to a water body.

This substantially odorless biologically mediated conversion of organicwaste results, in part, from the presence of diverse populations ofmicroorganisms in the treatment process. Although not limited to thesespecific populations, the low oxygen biologically mediated conversionprocess of the present invention is believed to be the result of thepresence, in significant quantities, of four microbial populationsincluding facultative heterotrophic fermentors, autotrophic nitrifiers,facultative heterotrophic denitrifiers, and autotrophic ammoniumdenitrifiers, as well as other organisms that coexist in this engineeredenvironment. Each microbial population contributes to the biologicallymediated conversion of the organic waste to nitrogen gas (N₂), carbondioxide (CO₂), water vapor (H₂O), clean water and beneficial soilproducts (humus) containing nutrients such as phosphorus (P) andnitrogen (N). Odorous compounds are not a product of the biologicallymediated conversion process.

The process comprises introducing organic waste containing sufficientconcentrations of total BOD and organic nitrogen (measured as TotalKjeldahl Nitrogen (TKN)) into a micro-electron acceptor environmentdefined by at least one cell, tank, pond, unit or the like, whereinresides a diverse microbial community comprising large populations offacultative heterotrophic fermentors, autotrophic nitrifiers,facultative heterotrophic denitrifiers, and autotrophic ammoniumdenitrifiers as well as other classes of organisms that coexist in thisengineered environment. The microbial populations within themicro-electron acceptor environment are brought into contact with thesubstrate of the organic waste via some means, generally includingagitation or mixing where the microorganisms exist as suspendedpopulations within the micro-electron acceptor environment, or byflowing the waste stream across settled or attached populations oforganisms, or by other contact means.

The amount of microorganisms within the biologically mediated conversionprocess is generally controlled to remove large cellulosic solids andlarge particulate solids and to concentrate microbes through the use ofrecycle loops, clarifiers or other solids concentrating or separatingtechniques (such as centrifugation or filtration). Excess microorganismsare removed from the micro-electron acceptor environment via a varietyof possible mechanisms to maintain favorable microbial health andviability. Preferably, all microorganisms generated in themicro-electron acceptor environment are eventually harvested, dewateredand/or dried to create a nutrient rich humus product, and/or they may betreated further and/or combined with other materials to create a varietyof differing nutrient rich humus products, such as, for example, animalfeed.

Dissolved oxygen concentrations are monitored within the micro-electronacceptor environment and when necessary, oxygen is introduced at ratesand in stoichiometric ratios so that the concentration of dissolvedoxygen does not exceed about 2.0 mg/L, and preferably does not exceedabout 0.1 mg/L. The increased rate of this low oxygen biologicallymediated conversion process of the present invention allows for reducedsize treatment facilities or makes it possible to treat a higher wasteload in an existing system. Further, the production rate of the nutrientrich humus material is also believed to potentially be enhanced.

Applicants have also discovered that adding or developing PAOpopulations which are functional in the micro-electron acceptorenvironment can result in an increase in the conversion of solublephosphorus within the organic waste stream into particulate form. Thenon-soluble phosphorus containing particulates, settleable and/orsuspended solids (which may include microbial cells, chemicalprecipitates, complexes and/or aggregates of cells, precipitates and/orother insoluble materials), can then be removed from the micro-electronacceptor environment as harvested humus material. Applicants havesurprisingly discovered that the improved nutrient removal of theprocess of the present invention can be achieved with the addition of ananaerobic environment and the continuous recycling of microorganismsbetween the micro-electron acceptor environment and the anaerobicenvironment.

Surprisingly, the improved nutrient conversion and removal occurs eventhough the process does not contain the relatively high concentrationsof oxygen, nitrate, nitrite and/or other electron acceptors that werepreviously thought to be necessary for such nutrient removal processes.It is well known in the art that an electron acceptor, such as oxygen,is required to achieve phosphorus removal which is why conventionalphosphorus removal systems typically utilize aeration to increasedissolved oxygen concentrations above 2.0 mg/L in an aerobic unitprocess. Most recently, high nitrate concentrations have been identifiedas a possible electron acceptor in place of oxygen. See Janssen, P. M.J., Biological Phosphorus Removal, Manual for design and operation, IWAPublishing (2002) at p. 18-20. In the process of the present invention,the concentrations of molecular oxygen, nitrate, and nitrite, ifexisting in the process at all, are very low individually, andcollectively.

Applicants believe that increased biologically mediated nutrientconversion according to the process of the present invention ispartially due to (i) the unique distribution of organisms in theprocess, particularly due to the additional presence, in significantquantity, of an additional group of PAOs, and (ii) the fact that despitethe very low concentrations of electron acceptors, substantial masstransfer reactions take place. In normal wastewater treatment where aBio-P process has been installed, the relative concentration of PAOs toother types of microorganisms is believed to be low. See Janssen, P. M.J., Biological Phosphorus Removal, Manual for design and operation, IWAPublishing (2002) at p. 20-21. This is true whether or not nitrificationand denitrification occurs in the process. However, in the process ofthe present invention, the relative concentrations of nitrifiers anddenitrifiers are believed to be higher than in conventional wastewatertreatment systems, and with the addition or development of themicro-electron acceptor phosphorus accumulating capability of theseorganisms, the process favors the further growth and maintenance of PAOdenitrifiers over the normal denitrifiers resulting in highconcentrations of nitrifiers and PAO denitrifiers.

High concentrations of nitrifiers means sufficient quantities ofnitrifiers are present such that when molecular oxygen enters theenvironment it is rapidly utilized by the nitrifiers to oxidize ammonia,which is available in high concentrations in the environment of thepresent invention, to nitrite and nitrate. High concentrations ofdenitrifiers means sufficient quantities of denitrifiers are presentsuch that when nitrite or nitrate enters the environment from theoxidization of ammonia by the nitrifiers, it will be rapidlydenitrified. In the process of the invention without appropriatelyinduced and maintained microbial populations with the micro-electronacceptor phosphorus accumulating capability, it is believed that normalnon-PAO denitrifiers will predominate over PAO denitrifiers since theyare more energetically efficient than the PAO denitrifiers. With thedevelopment and/or addition of appropriately induced and maintainedmicrobial populations with the micro-electron acceptor phosphorusaccumulating capability, the process confers a selective advantage onthe PAO denitrifiers over the normal denitrifiers and the Bio-P processwill predominate. Surprisingly, all of this still occurs in themicro-electron acceptor environment of the process in which molecularoxygen, nitrate, and nitrite each exist in very low concentrationsindividually and collectively. For example, nitrate concentrations inconventional wastewater treatment systems with nitrification aretypically in the range of 4-8 mg/L. The process of the present inventionoperates at nitrate concentrations below about 5 mg/L and can operate atconcentrations below about 0.5 mg/L. Thus, even though theconcentrations of electron acceptors are low, the high concentration ofPAO denitrifiers results in a rapid mass transfer through thedenitrifying process which still favors the PAO denitrifiers over thenon PAO denitrifiers.

Applicants believe that another possible reason that the developmentand/or addition of appropriately induced and maintained microbialpopulations with the micro-electron acceptor phosphorus accumulatingcapability can surprisingly induce additional quantities of solublephosphorus to be converted into particulate form is due to the uniquequantities and distribution of the microbial organisms in the process.The microbial organisms induce an environment favorable to theincorporation of soluble phosphorus into complexes which may includemicrobial cells, chemical precipitates, complexes and/or aggregates ofcells, precipitates and/or other insoluble materials, such that thesoluble phosphorus is captured in such aggregates and can then beremoved as harvested humus material leading to an effluent from thebiologically mediated conversion process which is low in solublephosphorus.

Applicants have also discovered that microbial populations with themicro-electron acceptor phosphorus accumulating capability cansurprisingly thrive without a physically separated and defined anaerobicenvironment. Denitrifying PAOs are not expected to have a selectiveadvantage to grow in low electron acceptor environments without aphysically separated and defined anaerobic environment. However,Applicants have determined that in the process of the invention, MEAPAOs(PAOs with the surprising ability to convert phosphorus without aphysically separated and defined anaerobic environment) will thrive whenthe anaerobic environment previously added to the process of theinvention is subsequently removed. This continued phosphorus conversioncapability is in stark contrast to all other known forms of enhancedbiological phosphorus removal, all of which require the presence of awell defined anaerobic zone. Applicants believe that the MEAPAOs'continued existence and functionality in the micro-electron acceptorenvironment of the present invention is due, in part, to the diversityand size of the microorganism population in the process.

Applicants have also surprisingly discovered that the increased nutrientconversion and removal process can be accomplished in the micro-electronacceptor environment without ever adding a physically separated anddefined anaerobic environment. This can be accomplished byadding/seeding the process of the invention with MEAPAOs that werecreated/developed elsewhere, perhaps at another facility where theprocess is operated and an anaerobic environment was added. Applicantsbelieve that the MEAPAOs will quickly acclimate and continue to functionin the process.

Lastly, Applicants have surprisingly discovered that MEAPAOs can evenfunction and thrive in the process of the invention without ever addinga physically separated and defined anaerobic environment and withoutseeding the process with MEAPAOs from another process. Applicantsbelieve that according to the process of the invention, through varyinglow concentrations of electron acceptors in local zones(microenvironments) of the larger micro-electron acceptor environmentcontaining relatively high phosphorus to nitrogen ratios (greater thanabout 0.16 and as high as about 0.3 to 0.5), MEAPAOs will develop andthrive. It is believed that the MEAPAOs will evolve through varyingmicroenvironments that approach an anaerobic state.

According to the process of the present invention, an influent wastestream containing P/N Ratios higher than about 0.17, and sometimes ashigh as about 0.30 to 0.50, or higher, can be treated and still haveeffluent discharges with low quantities of phosphorus. Approximately 50%or more of the influent waste stream soluble phosphorus can be convertedinto particulate form, incorporated into the humus material, and removedwhen that humus material is harvested.

DESCRIPTION OF THE DRAWINGS

FIG. 1 comprises a schematic illustrating the predominantinterrelationships of the organic waste, the major microbial groupsresponsible for biologically mediated conversion, the intermediatebreakdown substances, and the final products of the process of theinvention.

FIG. 2 comprises a flow diagram of an embodiment of the process of theinvention for a typical installation for a dairy farm.

FIG. 3 comprises a flow diagram of another embodiment of the process ofthe invention for a higher rate dairy farm system.

FIG. 4 comprises a schematic illustrating the predominantinterrelationships of the organic waste, the major microbial groupsresponsible for biologically mediated conversion, the intermediatebreakdown substances, and the final products of the process of theinvention with increased phosphorus removal.

FIG. 5 comprises a flow diagram of another embodiment of the process ofthe invention for a higher rate dairy farm system with increasedphosphorus removal utilizing a temporary/removable anaerobic zone orsub-zone

FIG. 6 comprises a flow diagram of another embodiment of the process ofthe invention for a higher rate dairy farm system with increasedphosphorus removal with the temporary/removable anaerobic zone orsub-zone removed from the process. FIG. 6 also comprises a flow diagramof another embodiment of the process of the invention for a higher ratedairy farm system with increased phosphorus removal with MEAPAO seeding.

FIG. 7 comprises a flow diagram of another embodiment of the process ofthe invention for a higher rate dairy farm system with increasedphosphorus removal utilizing a temporary/removable anaerobic zone orsub-zone.

FIG. 8 comprises a flow diagram of another embodiment of the process ofthe invention for a higher rate dairy farm system with increasedphosphorus removal.

DETAILED DISCLOSURE OF THE INVENTION

In the low oxygen biologically mediated conversion process of thepresent invention, evolution of a natural microbial community isencouraged under low dissolved oxygen conditions leading to a pluralityof desirable ecological niches. Further, when the flowable organic wastestream to the biologically mediated conversion process of the presentinvention contains relatively high concentrations of total BOD and TKN,and the TKN to total BOD by weight ratio is relatively high, e.g. whenthe mass ratio of TKN:total BOD is more than about 1:20 by weight, andpreferably more than about 2.5:20, the resulting low oxygen biologicallymediated conversion process can be an effective processing approach forrapid, substantially odorless, biologically mediated conversion of thewaste stream substrates (including nutrients).

When the influent oxygen loading and the dissolved oxygen concentrationin a biological treatment process are suitably regulated to maintain adissolved oxygen concentration of less than about 2.0 mg/L, preferablyless than about 0.1 mg/L, in the process, a series of compatible, andoverlapping and simultaneously occurring, ecological niches are formed.These niches so formed promote the growth and coexistence of desirablemajor populations of facultative heterotrophic fermentors, autotrophicnitrifiers, facultative heterotrophic denitrifiers, and autotrophicammonium denitrifiers over the growth inhibition of other microbialpopulations such as heterotrophic aerobes, which usually dominate thebacteria present in conventional wastewater treatment processes. FIG. 1comprises a schematic illustration of the interrelationships believed toexist between these microorganisms and the major substrates beingaffected during the biologically mediated conversion process of thepresent invention.

With reference to FIG. 1, populations of facultative heterotrophicfermentors 11 will thrive on the organic wastes 5 available, while thegrowth of obligate aerobes and obligate anaerobes, that might otherwisebe expected to compete for the carbon and energy sources, are suppressedby the very low dissolved oxygen concentrations maintained. There willgenerally be enough oxygen available to inhibit obligate anaerobes butnot enough to allow the obligate aerobes to be competitive.

In typical biological treatment processes, enough oxygen is supplied tothe facultative heterotrophs for complete biologically mediatedconversion of the carbon containing compounds. In the low oxygenbiologically mediated conversion process of the present invention, it isbelieved that the limitation of the oxygen concentration induces thefacultative heterotrophs to shift from an oxidative metabolism to afermentative metabolism. Thus, the facultative heterotrophic fermentorsferment the organics present to organic acids and/or alcohols instead ofoxidizing them through oxidative phosphorylation to carbon dioxide andwater.

The oxygen introduced into the process of the present invention is takenup by the autotrophic nitrifiers 12 to nitrify, generally by oxidizingto nitrite (NO₂ ⁻) and/or nitrate (NO₃ ⁻), the nitrogen containingcompounds in the system. In a typical biological treatment process, theorganisms with an oxidative metabolism take up the oxygen. Since theoxygen introduced into the process of the present invention appears tobe readily taken up by autotrophic nitrifier 12 populations, simplifiedcontrol systems can be used to control oxygen loading to promotenitrification in a low dissolved oxygen process, without promoting thecompeting growth of obligate aerobes and facultative heterotrophicmicroorganisms using oxidative phosphorylation. The desired dissolvedoxygen concentration for the process of the present invention is belowthe point where the organisms using facultative fermentative pathwayspredominate over organisms using oxidative pathways. Applicants havefound this dissolved oxygen concentration is less than about 2.0 mg/Land preferably, is less than about 0.1 mg/L. Generally oxygen present inthe process in excess of the requirements for nitrification by theautotrophic nitrifiers 12 will be used preferentially to supportheterotrophic aerobic activity. Within limits, the scavenging action ofthese heterotrophic aerobes removes the excess oxygen and maintains thepresent invention's oxygen concentration at very low levels.

Surprisingly, the low oxygen process of the present invention isbelieved to also use very low oxygen concentrations to establish apopulation of facultative heterotrophic denitrifiers 14 that use the NO₂⁻ and/or NO₃ ⁻ produced by the autotrophic nitrifiers 12 as theirelectron acceptor instead of dissolved oxygen. These facultativeheterotrophic denitrifiers 14 then convert the organic acids andalcohols produced by the facultative heterotrophic fermentors 11 andother waste stream organics present into CO₂ and H₂O, while reducing theNO₂ ⁻ and/or NO₃ ⁻ nitrogen to N₂. Sustaining low oxygen concentrationsthat are high enough to concurrently allow the autotrophic nitrifiers 12to thrive and nitrify ammonium (NH₄ ⁺) to NO₂ ⁻ and/or NO₃ ⁻ and lowenough to establish populations of facultative heterotrophicdenitrifiers 14 able to reduce NO₂ ⁻ and/or NO₃ ⁻ to N₂ is of benefit tothe current invention. This low oxygen environment also allows theestablishment of autotrophic ammonium denitrifiers 16 capable of usingNO₂ ⁻ to oxidize NH₄ ⁺ to N₂ and a small portion of NO₃ ⁻ in reducingCO₂ to cell material (biomass). Application of this concurrent orsimultaneous nitrification and denitrification process results in anutrient rich humus material made by a process for the substantiallyodorless biological treatment of solid and liquid organic wastes,particularly animal farm wastes.

Thus, referring to FIG. 1, applicants have found that controlling theamount of oxygen introduced into a biological treatment processcomprising a waste stream 5 having a relatively high concentration ofTKN and total BOD in a ratio of more than about 1:20 provides a strongniche for facultative heterotrophic denitrifiers 14. The organic acidsand/or alcohols produced by the facultative heterotrophic fermentors 11,together with other organics present in the waste stream and deadmicrobial cells or cell fragments, will efficiently combine with thenitrite and/or nitrate produced by the autotrophic nitrifiers 12 toprovide this strong niche for facultative heterotrophic denitrifiers 14and autotrophic ammonium denitrifiers 16. The facultative heterotrophicdenitrifiers 14 in turn denitrify the nitrite and/or nitrate to nitrogengas while the autotrophic ammonium denitrifiers 16 oxidize NH₄ ⁺ to N₂as well and return NO₃ ⁻ to the facultative heterotrophic denitrifiers14. Ultimately, the organic waste is converted to N₂, CO₂, H₂O, cleanwater and beneficial soil products. The low oxygen biologically mediatedconversion process of the present invention, therefore, provides forsubstantially odorless, efficient, treatment of organic waste.

Table 1 below provides example stoichiometric relationships thatillustrate the types of biochemical reactions that drive this process.

TABLE I EXAMPLE STOICHIOMETRIC RELATIONSHIPS 1) Fermentation of glucoseinto acetic acid by facultative heterotrophic fermentors: C₆H₁₂O₆ → 3C₂H₄O₂ 2) Cell synthesis by fermenting glucose into acetic acid byfacultative heterotrophic fermentors: 2 C₆H₁₂O₆ + 2 NH₄ ⁺ + 2 OH⁻ → 2C₅H₇O₂N + C₂H₄O₂ + 8 H₂O 3) Observed cell yields when fermenting glucoseinto acetic acid by facultative heterotrophic fermentors: 1.00 C₆H₁₂O₆ +0.05 NH₄ ⁺ + 0.05 OH⁻ → 0.05 C₅H₇O₂N + 3.025 C₂H₄O₂ + 0.20 H₂O 4)Endogenously nitrifying ammonia to nitrite by autotrophic nitrifiers: 2NH₄ ⁺ + 2 OH⁻ + 3 O₂ → 2 NO₂ ⁻ + 2 H⁺ + 4 H₂O 5) Cell synthesis bynitrifying ammonia to nitrite by autotrophic nitrifiers: 48 NH₄ ⁺ + 40HCO₃ ⁻ + 8 OH⁻ + 20 O₂ → 8 C₅H₇O₂N + 40 NO₂ ⁻ + 40 H⁺ + 72 H₂O 6)Observed cell yields when nitrifying ammonia to nitrite withNitrosomonas by autotrophic nitrifiers. USEPA, Manual: Nitrogen Control(1993), Office of Research and Development, EPA/625/R-93/010,Washington, DC: 1.0 NH₄ ⁺ + 1.44 O₂ + 0.0496 CO₂ → 0.01 C₅H₇O₂N + 0.990NO₂ ⁻ + 0.970 H₂O + 1.99 H⁺ 7) Observed cell yields when oxidizingnitrite to nitrate with Nitrobacter by autotrophic nitrifiers (fromUSEPA 1993): 1.00 NO₂ ⁻ + 0.00619 NH₄ ⁺ + 0.031 CO₂ + 0.0124 H₂O + 0.50O₂→ → 0.00619 C₅H₇O₂N + 1.00 NO₃ ⁻ + 0.00619 H⁺ 8) Observed cell yieldsfor the overall nitrification reaction of ammonia to nitrate byautotrophic nitrifiers (from USEPA 1993): 1.00 NH₄ ⁺ + 1.89 O₂ + 0.0805CO₂ → 0.0161 C₅H₇O₂N + 0.952 H₂O + 0.984 NO₃ ⁻ + 1.98 H⁺ 9) Endogenouslydenitrifying nitrite to nitrogen gas using acetate by facultativeheterotrophic denitrifiers: 3 C₂H₄O₂ + 8 NO₂ ⁻ + 8 H⁺ → 4 N₂ + 6 CO₂ +10 H₂O 10) Cell synthesis by denitrifying nitrite to nitrogen gas usingacetate by facultative heterotrophic denitrifiers: 95 C₂H₄O₂ + 32 NH₄⁺ + 40 NO₂ ⁻ + 8 H⁺ → 32 C₅H₇O₂N + 20 N₂ + 30 CO₂ + 146 H₂O 11) Observedcell yields when denitrifying nitrite to nitrogen gas using methanol byfacultative heterotrophic denitrifiers (from USEPA 1993): 1.00 NO₂ ⁻ +0.67 CH₃OH + 0.53 H₂CO₃ → 0.04 C₅H₇O₂N + 0.48 N₂ + 1.23 H₂O + 1.00 HCO₃⁻ 12) Endogenously and autotrophically denitrifying ammonium to nitrogengas using nitrite: 8 NH₄ ⁺ + 23 NO₂ ⁻ + 6 H⁺ → 11 N₂ + 9 NO₃ ⁻ + 19 H₂O13) Cell synthesis when autotrophically denitrifying ammonium tonitrogen gas using nitrite: 2 NH₄ ⁺ + 27 NO₂ ⁻ + 10 HCO₃ ⁻ + 10 H⁺ →N₂ + 25 NO₃ ⁻ + 2 C₅H₇O₂N + 5 H₂O 14) Observed cell yields for theautotrophic denitrification of ammonium to nitrogen gas using nitrite asan electron acceptor: NH₄ ⁺ + 1.32 NO₂ ⁻ + 0.066 HCO₃ ⁻ + 0.126 H⁺ → →1.02 N₂ + 0.26 NO₃ ⁻ + 0.066CH₂O_(0.5)N_(0.15) + 2.03 H₂O

Reaction numbers 1, 2 and 3 are examples of fermentation processesperformed by the facultative heterotrophic fermentors 11 using glucose(C₆H₁₂O₆) as the model carbon source and acetic acid (C₂H₄O₂) as themodel product. Reaction 1 shows the general fundamental relationship forthe endogenous energy producing reaction of the fermentation. Reaction 2shows the general fundamental relationship for the coupling of energyproduction with the synthesis of a microbial biomass (represented asC₅H₇O₂N). Reaction 3 shows how these two reactions are combined inactual operating conditions with experimentally observed cell yields.Although the reactions shown use glucose and acetic acid, as known bythose of ordinary skill in the art, many other compounds may besubstituted. For example carbohydrates, proteins, cellulosics, and/orother organic compounds containing oxygen may be substituted for theglucose; and ethanol, lactic acid, propionic acid, butyric acid, orother organic acids, alcohols, aldehydes, and the like may besubstituted for the acetic acid. These types of compounds, along withamino acids, peptides, nucleotides, and other compounds contained in theinfluent waste stream and/or resulting from microbial cell death andlysis, are known to serve as substrates similar to the acetic acid shownin the denitrification pathways represented by reaction numbers 9 and 10and the methanol shown in the pathway represented by reaction 11.

Reaction numbers 4, 5, and 6 depict the reactions for the nitrificationof ammonia by the autotrophic nitrifiers 12. Reaction 4 shows thegeneral fundamental relationship for the endogenous energy producingreaction in which ammonia is nitrified to nitrite. Reaction 5 shows thegeneral fundamental relationship for the coupling of reaction 4 withmicrobial cell synthesis. Reaction 6 illustrates how the combination ofreactions 4 and 5 describes the observed yields of microbial cells thatare synthesized during the nitrification of ammonia to nitrite byNitrosomonas type bacterial species. Conventional nitrificationprocesses employ a second step for the nitrification of nitrite tonitrate by Nitrobacter type bacterial species and this pathway may bepresent in the process of the current invention to varying degreesdepending on the specific dynamic operating conditions imposed. Incontrast, the process of the present invention utilizes facultativeheterotrophic denitrifiers 14 and autotrophic ammonium denitrifiers 16to denitrify the nitrite to N₂. However, if nitrate were present orproduced in the process of the present invention, the facultativeheterotrophic denitrifiers 14 would denitrify it to N₂ as well. Reaction7 shows this process relative to observed yields of microbial cells andreaction 8 shows the combined nitrification of ammonia to nitrate(reaction numbers 6 and 7), again relative to observed yields ofmicrobial cells.

Similarly, the reactions of the facultative heterotrophic denitrifiers14, reaction numbers 9, 10, and 11, show the biologically mediatedconversion of nitrite (similar reactions could be used to show thebiologically mediated conversion of nitrate) to N₂ gas. This isillustrated using general fundamental relationships, endogenously (9),and during cell synthesis (10), when using acetate as an electronacceptor. In reaction 11 the denitrification is shown relative toobserved yields of microbial cells and uses methanol (CH₃OH) as anelectron acceptor.

Reactions 12, 13, and 14 portray the autotrophic conversion of ammoniumand CO₂ to nitrate and N₂ by the autotrophic ammonium denitrifiers 16.As before, reaction 12 shows the endogenous process, reaction 13 showsthe process relative to cell synthesis, and reaction 14 shows thecombined process relative to observed cell yields. In reaction 14, themicrobial cell mass was represented as CH₂O_(0.5)N_(0.15) instead ofC₅H₇O₂N to reflect its publication reference. Astrid A. Van de Graaf,Peter de Bruijn and Lesley A. Robertson, Autotrophic Growth of AnaerobicAmmonium-Oxidizing Micro-organisms in a Fluidized Bed Reactor,Microbiology, 142:2187-96 (1996).

The nitrate produced in the autotrophic ammonium denitrificationreactions is consumed by denitrification reactions very similar to thoseshown in reactions 9, 10, and 11.

In order to attain and maintain dynamic equilibrium of ecologicalniches, it is important that enough growing microorganisms be present inthe total treatment system so that the population as a whole can evolveto optimally populate the four ecological niches in a reasonable timeperiod. Many waste streams are very complex, containing many differentchemical constituents, many of which contribute to both BOD and TKN.Consequently there are many possible fermentative pathways that thefacultative heterotrophs can use. The waste stream also provides evenmore possible substrates for the denitrification process including deadcells and cell fragments as well as the fermented products offacultative heterotrophic fermentors 11. A large dynamic microbialpopulation can evolve to optimally fit the available distributions ofmaterials in a waste stream and then can evolve to maintain this optimalfit as the waste stream and other environmental conditions, such astemperature, continually change. Thus, maintenance of a sufficientpopulation of microorganisms provides the system with efficientadaptability to system changes normally associated with wastewatertreatment systems. The larger the total population of microbes growingat a given average growth rate, the larger the number of mutations thatwill occur. Thus, the process of the present invention benefits from asufficient quantity of microorganisms to maintain a sufficient quantityof mutations, thereby providing for an efficient, dynamic biologicallymediated conversion process.

When optimizing the evolutionary criteria of a population of microbes,there is a preferred minimum population size and growth rate. This isexpressed as both a minimum mass of microbes and as a function of totalBOD and TKN loading. Generally the process of the present inventionrequires a minimum population of about 10¹⁵ microbes or more, with anaverage doubling time of about 30 days or less. A less efficient processof the invention can be achieved with a greater quantity of microbesregenerating at a slower rate (i.e. a larger doubling time). Preferably,the sustained minimum operating population is comprised of from about10¹⁷ to about 10¹⁸ microbes with a doubling time of about ten days orless, to ensure the presence of an adequate biomass to treat the wastestream. In addition to these minimum population size or mass criteria,it is also preferred to have at least about 10¹³ microbes with adoubling period of 30 days or less, per pound of influent total BOD orTKN. These two biomass parameters can alternatively be expressed as morethan about 10¹⁵ base pair replications per second for the minimumpopulation and about 10¹⁷ base pair replications per pound of total BODor TKN loaded into the treatment process. Most preferred values runabout 100 times these figures.

Thus, the beneficial results of the low oxygen biologically mediatedconversion process of the present invention are believed to be a resultof three general considerations. First, the process benefits from thepresence of a dynamically responsive, diverse, microbial community insufficient numbers or mass of microorganisms, growing at sufficientrates in the process, to allow the microbial community to adapt in aworkable time frame to achieve a dynamic equilibrium. Second, organicand nitrogen loading allows an energy, carbon and nitrogen balance tooccur between the microbial populations of facultative heterotrophicfermentors, 11 autotrophic nitrifiers 12, facultative heterotrophicdenitrifiers 14 and autotrophic ammonium denitrifiers 16. Third, controlof dissolved oxygen levels and/or oxygen additions creates and maintainsthe populations of facultative heterotrophic fermentors 11, autotrophicnitrifiers 12, facultative heterotrophic denitrifiers 14 and autotrophicammonium denitrifiers 16.

The low oxygen biologically mediated conversion process of the presentinvention is one in which the organic constituents contained in awaterborne waste stream, such as total BOD and TKN are converted to amixture of microbial cells, very stable refractory organic humus solidsand inert material, inert nitrogen gas, carbon dioxide, and water.

In a process of the present invention, a BOD and TKN containing wastestream, having a TKN:total BOD ratio of about 1:20 or more is introducedinto a micro-electron acceptor environment containing a microbialcommunity comprising large populations of facultative heterotrophicfermentors 11, autotrophic nitrifiers 12 facultative heterotrophicdenitrifiers 14 and autotrophic ammonium denitrifiers 16. The wastestream of BOD and TKN is brought into close contact with themicroorganism populations by any suitable means, preferably bymechanically mixing and/or by flowing the aqueous stream across settledor attached populations of organisms. The micro-electron acceptorenvironment of the process of the invention is generally contemplated asan open, bermed cell arrangement and is conveniently adaptable toautomated operation. However, closed tanks, cells or units could beutilized for the aqueous environment. Oxygen is introduced into thisenvironment at controlled rates and in specific stoichiometric ratios sothat the concentration of dissolved oxygen is maintained less than about2.0 mg/L and most preferably does not exceed about 0.1 mg/l. Theaeration means could be accomplished via diffused aeration, mechanicalmixers, surface mixers, surface atmospheric transfer, algal generationor other equivalent means. The concentrations of molecular oxygen,nitrate, and nitrite in the micro-electron acceptor environment are verylow, preferably below about 5 mg/L.

Solids in the micro-electron acceptor environment may be clarified byfloating or settling, thickened, centrifuged, separated or treated byother equivalent concentrating means and recycled to maintain thebiomass requirements. Excess microorganisms may be harvested, dewatered,and/or dried and sometimes further treated and/or combined with othermaterials to create a nutrient rich humus material that can bebeneficially used.

FIG. 2 illustrates a first embodiment of the invention in a dairy farmtreatment system. Wash water, liquid wastewaters 10 and/or recycledtreated flushing water 45 is used to transport and slurry the animalexcrement and wastes 27 from an animal confining barn, penning area orthe like 25 to a solids concentrating treatment unit 30 which acts as amulti-zone composting, solids dewatering and biologically mediatedconversion means. The solids concentrating treatment unit 30, could be aplurality of holding cells or zones, surrounded by containment bermswhich are generally arranged so that individual or sets of cells may beperiodically interrupted from the process so that their contents may beharvested, dewatered and/or dried for recovery of bioconverted organichumus. The principle function of the solids concentrating treatment unit30 is to convert excess biomass to an ecologically beneficial humusmaterial suitable for recovery. The process of the present invention,however, is not limited to the bermed holding cell. Other solidconcentrating treatment units 30, both open and closed to thesurrounding environment, such as clarifiers, flotation units, screens,filter presses, heat dryers, and the like could be used in addition toor in place of the bermed holding cell.

The solids concentrating treatment unit liquid effluent stream 32 istreated by a microorganism growth managing and enhancing unit 35 whereinmicrobes are grown, enhanced, modified and/or concentrated. Theprinciple function of a microorganism growth managing and enhancing unit35 is to promote the growth of biological microorganisms which entrainthe soluble material of the waste stream and continue the biologicallymediated conversion process. A microorganism growth managing andenhancing unit 35 generally comprises a suitably sized pond environment,tank, cell or the like.

The dissolved oxygen concentration and the amount of microorganisms inthe micro-electron acceptor portion of the process stream are monitored;specifically low dissolved oxygen and high microorganism quantity aresought to be maintained. Dissolved oxygen concentrations are controlledby means of aeration unit 36 that could include a dissolved oxygenaeration system, some type of mechanical mixers, enhanced naturalsurface aeration, submerged compressed air diffusers or the like. Thebiomass quantity is maintained by a biomass concentrating means 40 thatconcentrates the liquid effluent stream 37 from the microorganism growthmanaging and enhancing unit 35 and/or recycles it.

The treated microorganism growth managing and enhancing unit liquideffluent stream 37 is directed to the biomass concentrating means 40such as a clarifier wherein the biomass is settled and/or floated,thickened, separated and/or concentrated so that higher concentrationsof microbes can be recycled back to the microorganism growth managingand enhancing unit 35. Other treatment units besides clarifiers could beused to accomplish the biomass concentrating means 40. For example,settling tanks, cyclones, centrifuges, filter presses, filters, screens,and/or membranes could be used. Concentrated biomass sludge containinglarge quantities of living microbes is recycled via stream 42 back tothe influent end of the microorganism growth managing and enhancing unit35 to maintain biomass quantity therein. Alternatively, the concentratedbiomass sludge could be directed to and combined with the solidsconcentrating treatment unit liquid effluent stream 32, via stream 42 a,before entering the microorganism growth managing and enhancing unit 35,and/or it could be directed, via stream 43 a, to the influent end of thesolids concentrating treatment unit 30, and/or it could be directed toand combined with, via stream 43 b, the slurried animal excrement andwastes 27 before entering the solids concentrating treatment unit 30,and/or it could be removed from the system via stream 44 for conversioninto a beneficial humus material or other uses. The liquid effluent fromthe biomass concentrating means 40 (for example the overflow if aclarifier) could be used either as flush or wash water directed back viastream 45 to the barn, penning area or the like 25, and/or it could bedischarged from the system via stream 47 as a nutrient rich aqueousfertilizer for crops and/or it could be directed via stream 49 forfurther treatment prior to irrigation or discharge.

Ultimately, maintaining the process parameters, specifically the biomassand dissolved oxygen concentration parameters creates the micro-electronacceptor portion of the treatment system. In FIG. 2, the micro-electronacceptor portion includes the flowable portion of the solidsconcentrating treatment unit 30, the microorganism growth managing andenhancing unit 35 and the biomass concentrating means 40.

In an alternative embodiment, the liquid effluent from the biomassconcentrating means 40 undergoes further treatment. Clarified, settled,or separated effluent in stream 49 undergoes further biologicallymediated conversion in an additional microorganism growth managing andenhancing unit 52. The additional microorganism growth managing andenhancing unit effluent is directed, via stream 53, for further solids,total BOD and nutrient removal such as by means of a polishing unit 55.

A polishing unit 55 generally constitutes a flooded vegetative complexand preferably comprises a wetlands environment or overland flow systemmade up of plants and microorganisms suitable for capturing therelatively small quantity of nutrients contained in the effluentdischarged from a microorganism growth managing and enhancing unit 52.In a preferred embodiment, the polishing unit 55 generally comprisesmultiple, distinct cells arranged such that liquid discharged from amicroorganism growth managing and enhancing unit can be directed theretoin a variable and controlled manner. An especially preferred polishingunit generally comprises a suitable low lying field with a bermedperimeter and cross berms which create two or more liquid holding cells,wherein effluent from a microorganism growth managing and enhancing unitcan be variably directed to one or more cells of the polishing unit. Theliquid effluent from a polishing unit is sufficiently treated for reuse,wetland creation or maintenance, or discharge to a water body via stream60. As can be done for the solids concentrating treatment unit (stream62), a polishing unit 55 could be removed from service and the solidswithin could be harvested 64 and dried for humus material.

Alternately, conventional wastewater treatment processes could be usedto further treat the stream discharged from the biomass concentratingmeans 40 via stream 49, or from an additional microorganism growthmanaging and enhancing unit 52 via stream 53, to the quality desiredbefore recycle, reuse or discharge 60. In yet another embodiment, theprocess of the invention could be modified to speed up the biologicallymediated conversion process by removing solids that are digested at aslower rate by the microorganisms (i.e. cellulosic and course organicand inorganic solids) at the beginning of the process. This can beaccomplished by replacing solids concentrating treatment unit 30 with asolids separating means and adding another means of concentrating themicroorganism growth managing and enhancing unit liquid effluent stream37 to achieve the process' biomass retention requirements.

As shown in FIG. 3, wash water, liquid wastewaters 70 and/or recycledflushing water 110 are passed through an animal confining barn, penningarea or the like 75. The slurried animal excrement waste is directed via77 to a solids separating means 200, to separate cellulosic solids andother course organic and inorganic solids from soluble and finelysuspended solids. The separated stream is then directed to amicroorganism growth managing and enhancing unit 79 via stream 78wherein microbes are grown, enhanced, modified and/or concentrated. Thecoarse, mostly cellulosic solids, removed by the solids separating means200 are delivered by stream 205 to a mixer 95 for further processing ormay be removed from the system for other uses.

The dissolved oxygen concentration and the amount of microorganisms inthe micro-electron acceptor portion of the process stream are monitoredfor compliance with process parameters, specifically low dissolvedoxygen and high microorganism quantity. Dissolved oxygen concentrationsare controlled by means of aeration unit 82 that could include adissolved oxygen aeration system, some type of mechanical mixers,submerged compressed air diffusers or the like. The biomass quantity inthe system is maintained by concentrating and recycling the effluentfrom the microorganism growth managing and enhancing unit 79.

The treated microorganism growth managing and enhancing unit liquideffluent stream 85 is directed to a biomass concentrating means 89wherein the biomass is settled, thickened, separated and/orconcentrated. Further solids treatment for the concentrated biomass fromthe biomass concentrating means 89 is achieved by directing the solidsvia stream 92 to a solids mixer 95. Alternatively, these solids may beharvested via stream 93 for use as soil for plant growth productadditives, or for feed and food stocks or raw materials for suchprocessed stocks. The solids mixer 95 mixes the concentrated biomassfrom the biomass concentrating means 89 delivered to it via stream 92,with the cellulosic and other course solids separated from stream 77 bythe solids separator 200 that is delivered to the mixer via stream 205.Excess liquid is directed back to the microorganism growth managing andenhancing unit 79 via stream 97 and the mixed solids are removed viastream 99 and harvested, dewatered and/or dried to create a nutrientrich humus product.

The liquid effluent from the biomass concentrating means 89 is directedvia stream 101 to a solids clarifier 104 for further concentration ofthe solids. Concentrated biomass sludge from the solids clarifier isdirected via stream 108 back to the influent end of the microorganismgrowth managing and enhancing unit 79 to maintain biomass quantitytherein. The liquid effluent from the solids clarifier could either beused as flushing or wash water directed back via stream 110 to the barn,penning area or the like 75, and/or it could be discharged from thesystem via stream 114 as a nutrient rich aqueous fertilizer for cropsand/or it could be directed via stream 118 for further treatment priorto reuse or ultimate surface discharge into a wetland or water body, orby subsurface discharge to an underground aquifer, via stream 130.

The system parameters, specifically the biomass and dissolved oxygenconcentration are maintained in the microorganism growth managing andenhancing unit 79, the biomass concentrating means 89 and the clarifier104 in this embodiment.

Another embodiment of the invention includes further treatment forclarified, settled, or separated effluent in an additional microorganismgrowth managing and enhancing unit 120. The microorganism growthmanaging and enhancing unit effluent is directed, via stream 122, forsuch treatment by means of a polishing unit 124. The liquid effluentfrom a polishing unit is sufficiently treated for recycle, reuse ordischarge to a created, restored, enhanced, or constructed wetland orsurface or subsurface water body via stream 130.

The nutrient rich humus of the invention is a microorganism activeby-product of the biomass concentrating means 89, solids mixer 95 and/orpolishing unit 124 via stream 126.

Alternately, conventional wastewater treatment processes could be usedto further treat the stream discharged from the solids clarifier 104 viastream 118, or from the additional microorganism growth managing andenhancing unit 120 via stream 122, to the quality desired beforerecycle, reuse or discharge 130.

The process of the invention can also be modified to increase the amountof nutrients converted from soluble to particulate form. The addition ofan anaerobic zone or sub-zone wherein oxygen is not added, with periodicor continual recycling of all or a portion of the contents of theprocess through this anaerobic zone or sub-zone, can result in anincrease in the conversion of soluble phosphorus within the organicwaste stream into particulate form. The addition of an anaerobic zone orsub-zone, in conjunction with the other process parameters, subjects themicroorganisms to certain environmental conditions that can result in anincrease in the conversion of soluble phosphorus within the organicwaste stream into particulate form.

The process of the invention can then be further modified by removingthe anaerobic zone or sub-zone after the Bio-P functionality isestablished as evidenced by particulate phosphorus concentrations.Surprisingly, the phosphate accumulating/conversion ability of themicroorganisms continues despite the absence of a discretely definedanaerobic zone or sub-zone.

With reference to FIG. 4, populations of facultative heterotrophicfermentors 11 will thrive on the organic wastes 7 available, while thegrowth of obligate aerobes and obligate anaerobes, that might otherwisebe expected to compete for the carbon and energy sources, are suppressedin the micro-electron acceptor environment by the very low dissolvedoxygen concentrations maintained. There will generally be enough oxygenavailable in the micro-electron acceptor environment to inhibit obligateanaerobes but not enough to allow the obligate aerobes to becompetitive. By adding an anaerobic zone or sub-zone and thensubsequently removing or eliminating such zones or zone, conditions willfavor the persistence and development of appropriately induced andmaintained microbial populations with the micro-electron acceptorphosphorus accumulating capability without the need for a physicallydefined anaerobic environment. Most of these MEAPAOs, a subset of PAOs,will be facultative heterotrophic denitrifiers but some obligate aerobicMEAPAOs may be included as well. The MEAPAOs have the unique and novelability to thrive and function in the micro-electron acceptorenvironment.

Similar to the description for FIG. 1, the low oxygen concentration inthe micro-electron acceptor environment induces the facultativeheterotrophs to shift from an oxidative metabolism to a fermentativemetabolism. Thus, the facultative heterotrophic fermentors 11 fermentthe organics present to organic acids and/or alcohols instead ofoxidizing them through oxidative phosphorylation to carbon dioxide andwater.

In the process of the invention with MEAPAOs present, the oxygenintroduced into the process is taken up by the autotrophic nitrifiers 12to nitrify, generally by oxidizing to nitrite (NO₂ ⁻) and/or nitrate(NO₃ ⁻), the nitrogen containing compounds in the system. Since theoxygen introduced into the process of the present invention appears tobe readily taken up by autotrophic nitrifier 12 populations, simplifiedcontrol systems can be used to control oxygen loading to promotenitrification in a low dissolved oxygen process, without promoting thecompeting growth of obligate aerobes and facultative heterotrophicmicroorganisms using oxidative phosphorylation. The desired dissolvedoxygen concentration for the process of the present invention is belowthe point where the organisms using facultative fermentative pathwaysstart to predominate over organisms using oxidative pathways. Applicantshave found this dissolved oxygen concentration is less than about 2.0mg/L and preferably, is less than about 0.1 mg/L.

Generally oxygen present in the process in excess of the requirementsfor nitrification by the autotrophic nitrifiers 12 will be usedpreferentially to support heterotrophic aerobic activity. Normallyheterotrophic aerobic activity will be done by facultative heterotrophs,but may in some cases involve obligate aerobes as well. Within limits,the scavenging action of these heterotrophic aerobes removes the excessoxygen and maintains the present invention's oxygen concentration atvery low levels. With the addition or development of MEAPAOs forincreased phosphorus removal, Applicants believe that to the extentpresent, a significant portion of the heterotrophic aerobes in theprocess are PAOs capable of (i) competing with and establishing acompetitive advantage over the other oxygen utilizing microbialorganisms for a portion of the excess dissolved oxygen and (ii)absorbing additional phosphorus.

The process of the present invention is also believed to establish apopulation of heterotrophs, including facultative heterotrophs,denitrifiers (including MEAPAO denitrifiers) and MEAPAOs 18. The MEAPAOdenitrifiers and non-PAO denitrifiers use the NO₂ ⁻ and/or NO₃ ⁻produced by the autotrophic nitrifiers 12 as their electron acceptorinstead of dissolved oxygen. These denitrifying heterotrophs 18 thenconvert the organic acids and alcohols produced by the facultativeheterotrophic fermentors 11 and other waste stream organics present intoCO₂ and H₂O while reducing the NO₂ ⁻ and/or NO₃ ⁻ nitrogen to N₂.Sustaining low oxygen concentrations outside the anaerobic zone orsub-zone that are high enough to concurrently allow the autotrophicnitrifiers 12 to thrive and nitrify ammonium (NH₄ ⁺) to NO₂ ⁻ and/or NO₃⁻ and low enough to establish populations of facultative heterotrophsable to reduce NO₂ ⁻ and/or NO₃ ⁻ to N₂ is of benefit to the currentinvention.

This process also allows the establishment of autotrophic ammoniumdenitrifiers 16 capable of using NO₂ ⁻ to oxidize NH₄ ⁺ to N₂ and asmall portion of NO₃ ⁻ reducing CO₂ to cell material (biomass).

Application of this concurrent or simultaneous nitrification anddenitrification process results in a nutrient rich humus material madeby a process for the substantially odorless biological treatment ofsolid and liquid organic wastes, particularly animal farm wastes.

Thus, referring to FIG. 4, Applicants have found that controlling theamount of oxygen introduced into a biological treatment processcomprising a waste stream 7 having a relatively high concentration ofTKN and total BOD in a ratio of more than about 1:20 provides a strongniche for facultative heterotrophic denitrifiers 18. In addition, bytemporarily adding an anaerobic zone or sub-zone with recycle, a strongniche is also created and maintained for the development ofheterotrophic PAOs and subsequently, upon removal of the anaerobic zoneor sub-zone, development of the MEAPAOs 18, particularly for wastestreams with a relatively high P/N ratio of about 0.16, and sometimes ashigh as about 0.30 to 0.50 or higher. Once the MEAPAOs are developed,removal of the anaerobic zone or sub-zone does not remove the MEAPAOfunctionality as long as the low electron acceptor environment ismaintained.

The organic acids and/or alcohols produced by the facultativeheterotrophic fermentors 11, together with other organics present in thewaste stream and dead microbial cells or cell fragments, willefficiently combine with the nitrite and/or nitrate produced by theautotrophic nitrifiers 12 to provide this strong niche for heterotrophs18 and autotrophic ammonium denitrifiers 16. The denitrifyingheterotrophs 18 in turn denitrify the nitrite and/or nitrate to nitrogengas while the autotrophic ammonium denitrifiers 16 oxidize NH₄ ⁺ to N₂as well and return NO₃ ⁻ to the denitrifying heterotrophs 18.Ultimately, the organic waste is converted to N₂, CO₂, H₂O, clean water,and beneficial soil, and perhaps feed products. The low oxygenbiologically mediated conversion process of the present invention,therefore, provides for substantially odorless, efficient, treatment oforganic waste. With MEAPAOs present in the system, the amount ofphosphorus converted to particulate form most likely increases.

As shown in FIG. 5, wash water, liquid wastewaters 70 and/or recycledflushing water 110 are passed through an animal confining barn, penningarea or the like 75. The slurried animal excrement waste is directed toa solids separating means 200, to separate cellulosic solids and othercourse organic and inorganic solids from soluble and finely suspendedsolids. In the embodiment of the invention shown in FIG. 5, theseparated stream is then directed to a temporary/removable anaerobiczone or sub-zone 240 via stream 78 wherein a means of mixing 250 thatcould include some type of mechanical mixers, pumps, and the like, isused absent oxygen addition. The anaerobic zone or sub-zone 240 inducesquantities of soluble phosphorus to be converted into particulate formin the microorganism growth managing and enhancing unit 79 due to theunique quantities and distribution of microbial organisms in theprocess. PAOs in the anaerobic zone or sub-zone 240 encounter conditionsin which they will use energy stored in polyphosphate, therebydecreasing their polyphosphate stores, and will accumulate acetate orother volatile fatty acids, storing these compounds in polymer form,usually as polyhydroxybuteric acid.

The stream is then directed to a microorganism growth managing andenhancing unit 79 wherein microbes are grown, enhanced, modified and/orconcentrated, and wherein quantities of soluble phosphorus are convertedinto particulate form due to the unique quantities and distribution ofmicrobial organisms in the process. PAOs in the microorganism growthmanaging and enhancing unit 79 oxidize the stored organic polymers andother energy sources using electron acceptors and use the energy to formenergy rich polyphosphate. The polyphosphate is stored so that theenergy it contains may be used when anaerobic conditions recur, whichallows the PAOs to displace or viably compete with other heterotrophicmicroorganisms that can not take advantage of the stored energy tothrive under anaerobic conditions. This relative energy advantage in theanaerobic environment provided by the temporary/removable anaerobic zoneor sub-zone 240 leads to the dominance of PAOs over other non-phosphateaccumulating organisms which utilize oxygen as an electron acceptor.

The microbial organisms induce an environment favorable to theincorporation of soluble phosphorus into complexes which may includemicrobial cells, chemical precipitates, complexes and/or aggregates ofcells, precipitates and/or other insoluble materials, such that thesoluble phosphorus is captured in such aggregates and can then beremoved as harvested humus material leading to an effluent from thebiologically mediated conversion process which is low in solublephosphorus. If this biomass is then removed from the microorganismgrowth managing and enhancing unit 79 before the anaerobic zone orsub-zone 240 is encountered again, the phosphorus is removed from thesystem. The expected increase in the phosphorus content of the resultantbiomass and sludge reduces effluent phosphorus discharges.

Once a significant portion of the microbes in this process havedeveloped, the temporary/removable anaerobic zone or sub-zone 240 can beremoved. FIG. 6 shows the process of FIG. 5 without thetemporary/removable anaerobic zone or sub-zone. Once this removal of theanaerobic zone has occurred the MEAPAOs will perform the periodic andcyclical Bio-P functionality. However, in the absence of a large andwell defined anaerobic zone this increased phosphorus conversion isbelieved to occur as a response to small local variations in theconcentrations of electron acceptors relative to the individual MEAPAOs.The MEAPAOs will thus continually shift back and forth frompolyphosphate accumulation accompanied with PHB utilization mode to thepolyphosphate utilization accompanied with PHB synthesis mode inresponse to small variations in the concentrations of electron acceptorsin the local environment close to the microbe itself. The dimensions ofthese local environments may be as small as to be within a few micronsof the surface of the microbe itself.

The cyclical functionality of the MEAPAOs just described are believed topersist in a configuration as shown in FIG. 6 whether this functionalitywas generated as described relative to FIG. 5 in which an anaerobic zonewas initially present and then was subsequently removed, or whether thisfunctionality was derived from the addition of a population(s) ofMEAPAOs without ever adding a discretely defined anaerobic zone orsub-zone to the process.

In the embodiments of the invention shown in FIG. 5 and FIG. 6, thecoarse, mostly cellulosic solids, removed by the solids separating means200, are delivered by stream 205 to a mixer 95 for further processing ormay be removed from the system for other uses.

The dissolved oxygen concentration and the amount of microorganisms inthe micro-electron acceptor portion of the process stream are monitoredfor compliance with process parameters, specifically low dissolvedoxygen and high microorganism quantity. Dissolved oxygen concentrationsare controlled by means of aeration unit 82 that could include adissolved oxygen aeration system, some type of mechanical mixers,submerged compressed air diffusers or the like. The biomass quantity inthe system is maintained by concentrating and recycling the effluentfrom the microorganism growth managing and enhancing unit 79.

The treated microorganism growth managing and enhancing unit liquideffluent stream 85 is directed to a biomass concentrating means 89wherein the biomass is settled, thickened, separated and/orconcentrated. Further solids treatment for the concentrated biomass fromthe biomass concentrating means 89 is achieved by directing the solidsvia stream 92 to a solids mixer 95. Alternatively, these solids may beharvested via stream 93 for use as soil for plant growth productadditives, or for feed and food stocks or raw materials for suchprocessed stocks. The solids mixer 95 mixes the concentrated biomassfrom the biomass concentrating means 89 delivered to it via stream 92,with the cellulosic and other course solids separated from stream 77 bythe solids separator 200 that is delivered to the mixer via stream 205.Excess liquid is directed back to the microorganism growth managing andenhancing unit 79 via stream 97 and the mixed solids are removed viastream 99 and harvested, dewatered and/or dried to create a nutrientrich humus product.

The liquid effluent from the biomass concentrating means 89 is directedvia stream 101 to a solids clarifier 104 for further concentration ofthe solids. Concentrated biomass sludge from the solids clarifier isdirected via stream 108 back to the influent end of either the anaerobiczone 240 (as shown in FIG. 5) or the micro-aerobic zone 79 (as shown inFIG. 6) to maintain biomass quantity therein. The liquid effluent fromthe solids clarifier could either be used as flushing or wash waterdirected back via stream 110 to the barn, penning area or the like 75,and/or it could be discharged from the system via stream 114 as anutrient rich aqueous fertilizer for crops and/or it could be directedvia stream 118 for further treatment and/or storage prior to reuse orultimate surface discharge into a wetland or water body, or bysubsurface discharge to an underground aquifer, via stream 130.

The system parameters, specifically the biomass and dissolved oxygenconcentration, are maintained in the microorganism growth managing andenhancing unit 79, the biomass concentrating means 89 and the clarifier104 in this embodiment.

In another embodiment, further treatment and/or storage for clarified,settled, or separated effluent can occur in an additional microorganismgrowth managing and enhancing unit 120. The microorganism growthmanaging and enhancing unit effluent is directed, via stream 122, forfinal polishing by means of a polishing unit 124. The liquid effluentfrom a polishing unit is sufficiently treated for recycle, reuse ordischarge to a created, restored, enhanced, or constructed wetland orsurface or subsurface water body via stream 130.

The nutrient rich humus of the invention is a microorganism activeby-product of the biomass concentrating means 89, solids mixer 95 and/orpolishing unit 124 via stream 126.

Alternately, conventional wastewater treatment processes could be usedto further treat the stream discharged from the solids clarifier 104 viastream 118, or from the additional microorganism growth managing andenhancing unit 120 via stream 122, to the quality desired beforerecycle, reuse or discharge 130.

In another embodiment of the invention the addition (seeding) of anappropriate population of MEAPAOs into a micro-electron acceptorenvironment of the process with high levels of nitrogen and phosphoruscan lead to the presence, persistence, and further development of theBio-P capability. An example of this embodiment is also represented bythe process shown in FIG. 6, wherein the MEAPAOs 80 are added to themicroorganism growth managing and enhancing unit 79. Although thepreferred mode of operation is to add the MEAPAOs to unit 79, theMEAPAOs can be added anywhere in the process of the invention in liquidor solids form.

In other embodiments of the invention, the temporary/removable anaerobiczone or sub-zone may be located in other parts of the process, such asbefore, after or within the microorganism growth managing and enhancingunit 79, as long as part or all of the liquid contained in themicro-electron acceptor environment is periodically recycled through theanaerobic zone or sub-zone. Preferably, the temporary/removableanaerobic zone or sub-zone is located before or at the beginning of themicroorganism growth managing and enhancing unit 79.

In a further embodiment of the invention, it is believed that thedevelopment of MEAPAOs can be achieved and sustained by subjecting wastestreams with a relatively high P/N ratio of about 0.16, and sometimes ashigh as about 0.30 to 0.50 or higher to the process according to thepresent invention without seeding and without a temporary anaerobicenvironment. Instead, it is believed that the MEAPAO populationsgradually evolve and adapt through the cyclical variation of the localelectron acceptor concentrations in a low electron acceptor environmentleading to the presence, persistence, and further development of theBio-P functionality.

As shown in FIG. 7 wash water, liquid wastewaters 70 and/or recycledflushing water 110 are passed through an animal confining barn, penningarea or the like 75. The slurried animal excrement waste is directed viastream 77 to a contact mixing chamber 300 wherein all flushed orreceived wastes are mixed. The mixed wastes are then directed via 310 toa solids separating means 200, to separate cellulosic solids and othercoarse organic and inorganic solids from soluble and finely suspendedsolids. The separated stream is then directed via stream 78 to amicro-electron acceptor environment 79, which may contain atemporary/removable anaerobic zone or sub-zone, 240. Both thetemporary/removable anaerobic zone or sub-zone 240 and themicro-electron acceptor environment 79 may contain a means of mixing oraeration units 250 and 82, that could include some type of mechanicalmixers, pumps, and the like. The temporary/removable anaerobic zone orsub-zone 240 induces PAOs and MEAPAOs which cause quantities of solublephosphorus to be converted into particulate form in the microorganismgrowth managing and enhancing unit 79 due to the unique quantities anddistribution of the PAO and MEAPAO microbial organisms

PAOs in the temporary/removable anaerobic zone or sub-zone 240 encounterconditions in which they will use energy stored in polyphosphate,thereby decreasing their polyphosphate stores, and will accumulateacetate or other volatile fatty acids, storing these compounds inpolymer form, usually as polyhydroxybuteric acid.

The stream is then directed to a microorganism growth managing andenhancing unit 79 wherein microbes are grown, enhanced, modified and/orconcentrated, and wherein quantities of soluble phosphorus are convertedinto particulate form due to the unique quantities and distribution ofmicrobial organisms in the process. PAOs and MEAPAOs in themicroorganism growth managing and enhancing unit 79 oxidize the storedorganic polymers and other energy sources using electron acceptors anduse the energy to form energy rich polyphosphate. The polyphosphate isstored so that the energy it contains may be used when anaerobicconditions recur, which allows the PAOs to displace or viably competewith other heterotrophic microorganisms that can not take advantage ofthe stored energy to thrive under anaerobic conditions. This relativeenergy advantage in the anaerobic environment provided by thetemporary/removable anaerobic zone or sub-zone 240 leads to thedominance of PAOs over other phosphate uptake organisms which utilizeoxygen as an electron acceptor.

The microbial organisms induce an environment favorable to theincorporation of soluble phosphorus into complexes which may includemicrobial cells, chemical precipitates, complexes and/or aggregates ofcells, precipitates and/or other insoluble materials, such that thesoluble phosphorus is captured in such aggregates and can then beremoved as harvested humus material leading to an effluent from thebiologically mediated conversion process which is low in solublephosphorus. If this biomass is then removed from the microorganismgrowth managing and enhancing unit 79 before the temporary/removableanaerobic zone or sub-zone 240 is encountered again, the phosphorus isremoved from the system. The expected increase in the phosphorus contentof the resultant biomass and sludge reduces effluent phosphorusdischarges.

Once the Bio-P functionality has been developed, the temporary/removableanaerobic zone or sub-zone 240 may be removed from the process to give aconfiguration as shown in FIG. 8. This configuration would also apply inthe case where MEAPAO populations are added to the treatment system orto the case where the MEAPAO populations gradually evolved through thecyclical variation of the local electron acceptor concentrations in thelow electron acceptor environment. In these cases, the MEAPAOpopulations will continue to exhibit the Bio-P functionality induced byvariations in the local low electron acceptor concentrations. However,in the absence of a large and well defined anaerobic zone this phenomenawill now occur as a response to the small local variations in theconcentrations of electron acceptors relative to the individual MEAPAOorganisms.

In FIG. 8, the MEAPAO populations in microorganism growth managing andenhancing unit 79 will exhibit the enhanced Bio-P uptake behavior justdescribed independent of whether the MEAPAO populations were generated:(i) when certain environmental conditions are added to induce certainmicroorganism abilities and then such combinations are removed; (ii)when certain microbial populations having induced abilities are added,or (iii) when the low concentrations of electron acceptors are varied inlocal zones of a large environment containing relatively high phosphorusto nitrogen ratios (greater than about 0.16 and as high as about 0.3 to0.5).

The coarse, mostly cellulosic solids, removed by the solids separatingmeans 200 in FIG. 7 are delivered by stream 205 to a solids processingsystem 320 wherein solids maybe dried, composted, heat processed or thelike, or wherein the solids are land applied. Solids from the solidsprocessing system 320 can also be directed via stream 330 to theanaerobic zone or sub-zone 240 for further treatment in the process.

The dissolved oxygen concentration and the amount of microorganisms inthe micro-electron acceptor portion of the process stream are monitoredfor compliance with process parameters, specifically low dissolvedoxygen and high microorganism quantity. Dissolved oxygen concentrationsare controlled by means of mixing or aeration unit 82 that could includea dissolved oxygen aeration system, some type of mechanical mixers,submerged compressed air diffusers or the like. The biomass quantity inthe system is maintained by concentrating and recycling the effluentfrom the microorganism growth managing and enhancing unit 79.

The treated microorganism growth managing and enhancing unit liquideffluent stream 85 is directed to a biomass concentrating means 89wherein the biomass is settled, thickened, separated and/orconcentrated. Further solids treatment for the concentrated biomass fromthe biomass concentrating means 89 is achieved by directing the solidsvia stream 350 to solids treatment system 320 wherein solids may bethickened, dried, heated, sterilized, composted or otherwise processedfor use as humus material, feeds or feed supplements. Alternatively,these solids may be delivered via stream 355 to the anaerobic zone orsub-zone 240 or via stream 365 to the microorganism growth managing andenhancing unit 79, to control biomass concentrations.

Alternatively, the concentrated biomass from the biomass concentratingmeans 89 can be directed via stream 360 to solids storage unit 370 forultimate disposal on land or by other means 130.

The system parameters, specifically the biomass and dissolved oxygenconcentration are maintained in the microorganism growth managing andenhancing unit 79 and the biomass concentrating means 89 in thisembodiment.

The nutrient rich humus material of the invention is a microorganismactive by-product from the biomass concentrating means 89.

Alternately, conventional wastewater treatment processes could be usedto further treat the stream discharged from the biomass concentratingmeans 89 via stream 360 to the quality desired before recycle, reuse ordischarge 130.

In other embodiments of the invention, the temporary/removable anaerobiczone or sub-zone 240 may be located in other parts of the process, suchas before, after or within the microorganism growth managing andenhancing unit 79, as long as part or all of the liquid contained in themicro-electron acceptor environment is periodically recycled through theanaerobic zone or sub-zone during the MEAPAO development period.Preferably, the temporary/removable anaerobic zone or sub-zone 240 islocated before or at the beginning of the microorganism growth managingand enhancing unit 79.

The process of the invention could be further modified for otherapplications. For example, a standard hog farm system according to thepresent invention might advantageously incorporate an additionalmicroorganism growth managing and enhancing unit in between the barn andthe solids concentrating unit.

A process of the present invention may include a chemicaladdition/mixing sub-zone within a microorganism growth managing andenhancing unit or positioned in one or more cells of a solidsconcentrating treatment unit 79. Such a sub-zone could be positioned formixing in chemicals that could be added to the process of the inventionto essentially chemically perform the role of the facultativeheterotrophic fermentors and/or for mixing in metallic salts or organicpolymers for the removal of precipitable phosphorus and other materials.Preferably, such a sub-zone is positioned at the influent end of amicroorganism growth managing and enhancing unit 79 or biomassconcentrating means 89. In such an embodiment, although the facultativeheterotrophic fermentors would still be present in the process of theinvention, albeit in smaller quantities, chemicals can be added to theprocess of the invention to supply an energy source for the facultativeheterotrophic denitrifiers. For example, acetic acid, methanol, or otherorganic acids or alcohols could be used. Preferred metallic salts forthis purpose include ferrous sulfate, ferric chloride, alum and the likewhich can combine with suspended and/or solubilized phosphorus compoundsto form a precipitate and/or associated chemical complexes.

In another embodiment, a system using the process of the invention mayhave one or a series of closed vessels, the vessels being initiallyloaded with a microbial population of about 10¹⁵ microbes or more, andbeing in fluid communication with an influent aqueous waste streamhaving a concentration of total BOD and a ratio of TKN:total BOD of morethan about 1:20. The vessel includes means for delivery of oxygenthereto, preferably comprising a combined mechanical mixing and aerationmeans, arranged to be automatically enabled as desired.

The process of the present invention could further comprise a pluralityof sensing means, arranged to sense dissolved oxygen and/or oxygenloading, biomass and/or influent stream temperature and rates ofinfluent flow, each being interconnected to a central processing unit.Sensing means, for example, may include oxidation/reduction potential(redox), pH, conductivity, temperature and/or combinations thereof aloneor together with other sensors, which enable data indicative of dissolveoxygen concentration and/or availability. Other sensing means whichrelate to the functionality, stability, and/or performance of thesystems as a whole or the microbial biomass, may also be used in theprocess of the invention. These might include liquid sensors, such asspecific ion electrodes for a variety of ions including ammonium ions,and gas sensors which could detect ammonia and other nitrogen containinggaseous compounds, hydrogen sulfide, mercaptans, and a variety ofvolatile organic compounds such as the acetic, butyric, and propionicacids commonly associated with ruminant manures.

A central processing unit such as a computer, typically comprisingmicro-controller means, data distribution means, data storage means andcomparator/computing means may be used. Data from at least one or aplurality of sensing means is typically routed to the micro-controllermeans, wherein it is digitized for use by the central processing unitand provided to the distribution means for distribution to thecomparator/computing means and/or data storage means. Thecomparator/computing means generally compares data received from thedistribution means with previously stored data and analyzes, computesand/or confirms system parameters within the biomass, thereby enabling,disabling or varying oxygen loading and/or mixing and/or recycle flowsand/or influent waste stream flow in accord with preset and/orcontinually calculated system parameters. A monitor and/or printerprovides visual and/or hard copy confirmation of status and the centralprocessing unit may be interconnected to a remote station to enableremote monitoring and remote system modification as desired.

In a further preferred embodiment, a vessel will automatically dischargesuitably bioconverted product for subsequent processing and retain anappropriate quantity of biomass containing the appropriate mass ofmicrobes for managed treatment of the aqueous influent stream.

The efficiency of the process of the present invention is best describedby example. In a typical wastewater application of the presentinvention, 100 pounds of TKN and 260 pounds of total BOD can be treatedwith 260 pounds of oxygen, to produce 105 pounds of cells whiledischarging essentially no TKN in the effluent and predominatelydischarging N₂ and CO₂ to the atmosphere. In comparison, an advancedwastewater treatment plant using costly energy intensive nitrogenremoval technology would require more than 600 pounds of oxygen toachieve the same discharge criteria. In further comparison, aconventional secondary treatment wastewater plant, would use about thesame 260 lbs. of oxygen as the process of the invention, just to treatthe BOD, while a significant part of the influent TKN nitrogen would bedischarged to the atmosphere as ammonia gas, with most of the remainderof TKN being discharged in the effluent stream as ammonium ions and TKN.

The process of the present invention is applicable to multiple diversewastewater streams. For example, the process is applicable to municipalwastewater streams containing a total BOD of about 100 to about 400mg/L, a TKN of about 10 to about 70 mg/L and a total Phosphorus of about4 to about 15 mg/L; to flushed wastewater from a hog, dairy and/or otheranimal holding area having a total BOD of about 500 to about 16,000mg/L, a TKN of about 100 to about 3,000 mg/L and a total Phosphorus ofabout 30 to about 2,500 mg/L; and industrial, food processing and thelike wastewater having a total BOD of about 400 to about 80,000 mg/L anda TKN of about 20 to about 10,000 mg/L. Additional application areasinclude the production of a microbial cell mass for single cell proteinproduction from a variety of biodegradable materials, e.g. solid and/orwaterborne, and appropriate nitrogen sources.

The nutrient rich humus of the invention is a settled and in some casesprecipitated, microorganism active-product of the process. The humuscomprises bioconverted organic waste containing stable nitrogen,phosphorus and potassium rich material, bound in an active microorganismmatrix intermixed with fibrous cellulosic and/or other organicmaterials. The appearance of dried humus varies significantly from driedmanure in that it is a deep brown, peat like or granular material, whichreadily mixes with soil, including clay, sand and the like. The materialis substantially generally absent an offensive odor and has limited odorthat is closely similar to that of rich topsoil. The material may becomminuted (ground, granulated, screened, milled) and generally containsfew clumps. The material is generally hydrophobic in that it resistswetting, but once wetted it becomes hydrophilic in that it tends to holdwater. The material appears to resist clumping even when wetted.

A preferred humus of the invention, without provision for increasedphosphorus removal, comprises from about 0.2 to about 6.0% nitrogen,about 0.1 to about 2.0% phosphorus and from about 0.1 to about 2.0%potassium on a dry weight basis, in stable form. The use of chemicalprecipitation and high rate processing can raise the nitrogen,phosphorus and potassium upper limits to about 10% on a dry weightbasis.

A more preferred humus of the invention, with increased phosphorusremoval, comprises from about 0.2 to about 12.0% nitrogen, about 0.1 toabout 14.0% phosphorus and from about 0.1 to about 4.0% potassium on adry weight basis, in stable form. The use of chemical precipitation andhigh rate processing can raise the nitrogen, phosphorus and potassiumupper limits.

Though unstable nitrogen and phosphorus values are generally present inthe humus of the invention, they appear to be in quantities so low as toconstitute little or no environmental threat through aqueous dissolutionand run-off, but are available for uptake by plants. Thus, the humus ofthe invention is unique in that the nitrogen and phosphorus nutrientrich character thereof is in a form beneficial for enhancing the growthof vegetation within its environment, yet resistant to migration byrainfall, ground water flow and the like to pollution of aquifer,surface and groundwater accumulations.

The humus of the invention created from animal excrement could compriseother components which are defined by the animal feed supply, the animalfrom which the humus is generated, any bedding, parlor washwaters,cleaners, run-off and the like, or other materials which may becollected or added to the system for humus generation. Such other addedcomponents are synergistic and are intended to improve the efficacy of aparticular humus of the invention for a particular use.

The organic matrix of the humus of the invention is rich in stabilizednutrient content and comprises dynamic macro and/or micro organisms andother components which appear especially predisposed to proactivelyadapt and interact with additive materials in an efficacious phenomenawhich can be managed to provide a host of further beneficial products.

Due to the maintenance of the process parameters in the desired ranges,a consistent quality of humus can be obtained. Waste may be collectedfrom any convenient organic waste source such as dairy cows, sheep,goats and the like, feed lot cattle, swine, horses, zoo animals, poultryincluding chicken, turkeys, ducks and the like and even aquatic animalssuch as fish, frogs and alligators.

The process of the invention is managed to maximize the active,facultative heterotrophic and autotrophic biomass by continuallygenerating genetic variations in its organisms to optimize microbialadaptability of the biomass to survive and thrive in varyingenvironments. The humus harvested has an active microbial potential thatappears to adapt to environmental changes with a host of interestingbeneficial effects. Thus, the humus of the invention, which comprisescaptured and stabilized nutrients along with trace metals, appears toadapt and capture toxic substrates or trace metals when produced from ormixed with a waste stream containing same. Microbial variations whichappear to degrade cellulose and lignin are enhanced by microbialvariations which appear to degrade other polymerized materials.Microbial variations which appear to capture and stabilize nutrients areenhanced by microbial variations which appear to promote seedgermination and release of nutrients which increase crop yield and sizeof fruits, grains and vegetables.

The humus of the invention is generally processed after harvesting forboth convenience of handling and enhancement of microbial activity.Generally, the humus of the invention is at least partially dried toreduce its handling weight by air drying, vacuum water removal, mildheat drying or the like and thereafter shredded, screened, pulverized orthe like as may be desired. It is also possible to use other dryingprocesses or techniques such as intense heat drying, forced air, orcyclonic drying. It should be understood however, that the humus of theinvention need not be dried or further comminuted to be effective as abeneficial product in accord with the invention.

Partially dried and processed humus is easily mixed with other materialsand has been found to be especially effective in providing an enhancedgrowth media when mixed with normal soils and top soils.

The humus of the invention can also be effective in producing remediatedgrowth soil media when mixed with clay, sand, silt, mud, soil, gravel,dust, mine tailings, dredge materials, depleted or spent soils and thelike. New growth media can be created through mixtures of the humus withsawdust, paper, cardboard, polymers, plastics, waste organics oragricultural materials such as bagasse, hulls, stalks, stems, waste hay,leaves, shells, cotton or rayon dust and the like.

It is contemplated that the humus of the invention can also be used inaquatic growth environments wherein the humus alone or mixed as aboveindicated with other media is added to a flooded environment for plantgrowth. This could be used for the creation, restoration, or enhancementof wetlands.

Though the humus of the invention provides enhanced nutrient content topromote germination and growth of plants, it has also been found to beeffective in suppressing plant disease and providing plant pestresistance. Humus which is harvested direct from the process of theinvention is generally too nutrient rich to be a suitable plant growthmedia standing alone, and is generally mixed with an appropriatematerial as above described to provide a desirable medium. Interestinglyhowever, such directly harvested humus appears to provide a good topcover for plants which have been seeded or germinated in under soils,appearing to provide resistance to the spread of disease bacteria andthe like while providing a rich nutrient source which can be utilized bythe root structure of the existing plant.

The humus of the invention can also be an effective feed component.Depending upon the animal source of the waste used to generate the humusof the invention, the humus can be of beneficial utility as a feed stockand/or additive. For example, the humus produced from the waste fromtypical swine feed lot operations generally comprises protein contentwhich appears to define and characterize a delivery vehicle fornutrients, trace elements and the like for feed stock utility.

Thus, humus generated from barn and manure waste from a trough fed dairycow or feed lot operation comprises an active organic matrix which maybe characterized differently from that of a grazing fed dairy cowoperation, which is different from a hog feed lot operation and/orchicken or turkey lot operation. Though each such operation produces anutrient rich humus which has general applicability for plant growth,each operation also results in a humus containing other components whichgenerally contribute to an individual humus being particularly suitablefor specific utilities such as enhanced germination and growth ofspecific plants and/or remediation of specific soils and/orcharacterization as foodstuffs or feed additives. The humus of theinvention can be modified to achieve specific objectives by introducingvarious materials into the influent flush waters to the process or intovarious other components of the process. The nature of the addedmaterial and the manner and location of its addition will influence theadaptive and biodynamic character of the process and the resulting humusor other byproduct material. This can be managed to achieve a variety ofdesirable end product uses and functions.

1. A population of MEAPAOs adapted to grow in a cell, tank, pond, orunit containing organic waste, without a physically separated anddefined anaerobic environment, wherein oxygen is maintained at less thanabout 2.0 mg/L of dissolved oxygen, wherein the concentrations ofnitrate and nitrite are each less than about 5 mg/L, and wherein saidMEAPAOs are capable of increased conversion of at least one nutrientfrom soluble to particulate form in said cell, tank, pond, or unitamounting to removal of at least about 30% of influent phosphorus in abiological treatment process with solids removal.
 2. The population ofMEAPAOs of claim 1, wherein said increased conversion of one nutrientfrom soluble to particulate form amounts to removal of at least about50% of influent phosphorus.
 3. The population of MEAPAOs of claim 1,wherein said increased conversion of one nutrient from soluble toparticulate form amounts to removal of at least about 80% of influentphosphorus.
 4. The population of MEAPAOs of claim 1, wherein theinfluent to the biological treatment process comprises a P/N Ratio aboveabout 0.17.
 5. The population of MEAPAOs of claim 1, wherein theinfluent to the biological treatment process comprises a P/N Ratiobetween about 0.3 to 0.5.
 6. A population of micro-organisms comprisinga population of MEAPAOs characterized in that said MEAPAOs are capableof increased conversion of at least one nutrient from soluble toparticulate form in a cell, tank, pond, or unit containing organicwaste, without a physically separated and defined anaerobic environment,wherein oxygen is maintained at less than about 2.0 mg/L of dissolvedoxygen, and wherein the concentrations of nitrate and nitrite are eachless than about 5 mg/L, wherein said increased conversion of onenutrient from soluble to particulate form amounts to removal of at leastabout 30% of influent phosphorus in a biological treatment process withsolids removal.
 7. The population of microorganisms of claim 6, whereinsaid increased conversion of one nutrient from soluble to particulateform amounts to removal of at least about 50% of the influentphosphorus.
 8. The population of microorganisms of claim 6, wherein saidincreased conversion of one nutrient from soluble to particulate formamounts to removal of at least about 80% of the influent phosphorus. 9.The population of microorganisms of claim 6, wherein the influent to thebiological treatment process comprises a P/N Ratio above about 0.17. 10.The population of microorganisms of claim 6, wherein the influent to thebiological treatment process comprises a P/N Ratio between about 0.3 to0.5.